Co-pending application Ser. No. 850,630, filed Apr. 11, 1986 entitled LED-Array Image Printer, commonly assigned with the present application and hereby incorporated by reference, discloses an LED Array Image Printer for contact or non-contact printing wherein a carriage mounted LED-array is scanned perpendicular to the direction of travel of a photosensitive medium. The carriage is scanned across the photosensitive medium by a motor and belt drive mechanism. The preferred embodiment of the foregoing application discloses a print head having a pressure foot which contacts the photosensitive medium during the scan to maintain proper positional alignment between the LED-array, imaging lens and photosensitive medium. The foregoing application also contemplates that the scanning system could be non-contact if a stable distance could be provided between the lens and the photosensitive medium.
Although the LED-Array Image Printer disclosed in the foregoing application represents a significant advance in the art of low cost, high speed image printers, it has been found that the carriage assembly and drive mechanism there disclosed do not lend themselves well to non-contact printing. In short, the carriage assembly and drive mechanism do not achieve a sufficiently stable distance between the lens and photosensitive medium to achieve a high quality non-contact printed image. Indeed, the belt driven carriage assembly of the foregoing application is relatively flexible and may experience backlash. These characteristics prevent the belt driven carriage from achieving a sufficiently stable imaging distance across the scan to provide non-contact printing.
Thus, although the advantages of non-contact printing, e.g. elimination of frictional contact between a pressure foot and the photosensitive surface, are appreciated by the foregoing application the scanning head drive carriage assembly there disclosed does not achieve sufficiently reliable stability to obtain non-contact imaging.
Therefore, it is one object of the present invention to provide an improved non-contact LED-Array Image Printer.
It is a further object of the present invention to provide, in a non-contact LED-array image printer, a drive carriage assembly which maintains a stable distance between the imaging lens and the photosensitive surface.
Another object of the present invention is to provide a carriage and drive assembly for an LED-array image printer which does not experience backlash effects.
These and other highly desirable and unusual results are accomplished by the present invention in a low cost structure which achieves high quality non-contact imaging.
Objects and advantages of the invention are set forth in part herein and in part will be readily appreciated herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.